A new case of 'not knowing his arse from his elbow' has been confirmed at a fourth farm tonight.
DEFRA officials moved in shortly after noon to isolate Boris Johnson from all other MPs in the House of Commons.
Experts were fearful that the disease might spread across the whole of the Government, prompting a wholesale cull of all politicians within a 100 mile radius.
However many were warning that the Arse from Elbow virus had gone undetected for many years, at least since the bovine Margaret Thatcher took power.
Professor Gibbering Wreck BSc told reporters: 'Victims of this disease will quite often speak complete gibberish and utter bollocks.
'It is almost impossible to separate the healthy politicians from those infected with Arse from Elbow.
'Therefore I recommend that all MPs be incinerated immediately, including Prime Minister Gordon Brown.'
The Prime Minister called an urgent press conference at which he proceeded to chomp on the leg of the aforementioned Boris Johnson with glee.
Mr Brown said: 'I hereby pronounce that Boris Johnson is the tastiest morsel I have ever devoured - better even than Tony Blair, who I chewed on repeatedly for the last four years of his Premiership.'
The latest victims of the Arse from Elbow contagion were last night confirmed as Tory leader David Cameron and Liberal Democrat sage Menzies Campbell.
On hearing the news, the Lib Dem leader merely repeated the word Ming over and over again inexplicably.
However David Cameron was wholeheartedly endorsed by the Conservative Party, who have recently seen their ranks decimated by the 'Unelectable' virus.
So far 43 politicians have been incinerated in front of a cheering crowd at Hampstead Heath, London.
The Prime Minister's announcement did not satisfy all consumers of politics and many were determined to boycott all dealings with Members of Parliament.
Harold Bishop, 64, said: 'I have voted for these people time and time again and if I have been infected with Arse and Elbow I will be devastated.
'My trust in the Democratic principle has been shattered.'
Scientists said Boris Johnson was identified as a risk after he told listeners on Radio Five Live 'Muslims are just Jews with beards.'
The MP added: 'I like bottoms. A lot.'